BIOLOGY IN ITS WIDER ASPECTS 1255 



It will repay us to use the simple graph of Fig. 200, especially if 

 it can be considered not on the flat, but in the three dimensions. 

 For instance, suppose the organism should degenerate, then how apt 

 it is to draw both the function and the environment down with it, 

 a very familiar change in the human tragedy. But suppose the 

 organism has an uplift, then how strong it often is to draw its envi- 

 ronment and function up with it. If one interprets the basal line as 

 functioning in the wide sense, it may serve to represent the exertions 

 man takes to keep fit, to find shelter, to get on and so forth. When 

 the struggle is too keen and the base too long drawn out, as often 

 happens, how apt is this to depress both the organism and the 

 environment. In some places, known to us all, where the struggle 

 for existence is terribly keen, the organismal life has lost much of its 

 pitch and the environment has sunk to a dreary monotony. Part of 

 the human ideal is to shorten the necessary activities for mere 

 sustenance, and to lengthen the other two sides of the triangle, the 

 organism's own life and the environment. Perhaps mankind is 

 moving towards a compression of the efforts that are necessary for 

 gaining subsistence and the like; and this will be to the good if it is 

 associated with a raising of the pitch of the organismal life and the 

 beautifying of the environment. Secure progress depends not a 

 little on an understanding of the biological prism. 



There is a little worm, Planaria, about the length of half one's 

 little finger-nail, a simple and interesting creature, which has been 

 more experimented with than any other animal except the tadpole. 

 If a young Planaria is reared on the minced flesh of the freshwater 

 mussel — a food which it dislikes — it grows in a sulky sort of way. 

 It soon stops growing, and becomes an old youngster that does not 

 grow up — and all because it was forced to eat a kind of food that did 

 not suit it. How quaintly suggestive this is as to the value of a varied 

 diet, as to the risk of too much porridge, at the one extreme, and 

 toujours perdrix at the other ! 



It is a mistake to think that this relation of the organism to the 

 environment is at all an easy subject. Suppose we draw a circle, 

 place the organism in the middle, and try to see in what different 

 ways the organism may influence the environment, and how in its 

 turn the environment may play upon the organism. See the organism 

 throughout its life running the gauntlet of never-ending environ- 

 mental influences — mechanical, chemical, physical, animate. These 

 influences take many forms, (i) Thus, to begin with, the organism 

 is entirely dependent on its surroundings. The effect of taking 

 the organism wholly out of its essential environment is familiar in 

 the fish out of the river. Take away the oxygen, for instance, and 

 life is over. (2) Secondl}^, the organism is stimulated by its environ- 

 ment. When we go out into the sunshine our pulse changes its 

 rhythm, and it is easy to prove that we enjoy the sunshine quite 



